Students in Melissa Williams' kindergarten class at the Westminster School in Atlanta, Georgia, practice connecting quantities to written numbers — a key part of number sense. Credit: Holly Korbey for ...

Imagine winding the hour hand of a clock back from 3 o’clock to noon. Mathematicians have long known how to describe this rotation as a simple multiplication: A number representing the initial ...

Use Base-Ten diagrams and standard, expanded, and word forms to represent numbers. Warm up with a Mystery Math Mistake as you add two 2-digit numbers using a decomposition strategy. Find Which One ...

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